JP2016524338A - Die package with low electromagnetic interference wiring - Google Patents

Abstract

A die package having a lead structure for providing electromagnetic interference reduction and connecting to a die. A mixed impedance lead connected to the die includes a first metal core, a dielectric layer covering the first metal core, and a first lead having a first outer metal layer connected to ground. And a second metal core, a dielectric layer covering the second metal core, and a second lead wire having a second outer metal layer connected to the ground. Each lead reduces susceptibility to EMI and crosstalk.

Description

  The present invention relates to a novel lead structure that reduces electromagnetic interference and connects to a die. Implementation of the present invention reduces susceptibility to noise caused by crosstalk between leads, electromagnetic emissions inside or outside the package.

  Furthermore, the present invention relates to a novel multi-ground plane formed to connect dielectric coated leads that connect to one or more dies.

  Electromagnetic interference leading to performance degradation has become a common problem for packaged dies, particularly dies with input / output (IO) operating at gigahertz frequencies. Many integrated circuits generate an undesirable amount of EMI. In general, the noise generated by an integrated circuit is due to the connection of the die to the pins of the die through the package. When EMI couples to adjacent components or integrated circuits, EMI can interfere with their individual performance and affect overall system performance. Because of the adverse effects of EMI, acceptable radiated EMI levels are subject to strict regulatory limits, so it is desirable to prevent or suppress EMI generated from integrated circuits.

  Solutions such as lead separation or shield insulation are not always available or sufficient. Furthermore, EMI solutions at the IC package level are often neglected because the main issues at that level are signal transmission quality and functionality. EMI solutions at the package level are useful because they help eliminate the need for “downstream” or add-on solutions.

  In view of the problems and disadvantages of the prior art, it is an object of the present invention to provide a compact die package with excellent signal transmission quality and functionality, in particular a stacked die package having two or more lead wires and / or Or to provide a BGA package.

  The above and other objects that will be apparent to those skilled in the art are achieved by the present invention directed to a die package for EMI attenuation, the die package comprising a die having a plurality of connection pads and a plurality of connection elements. A die substrate that supports the first metal core, a first metal core having a first metal core diameter, a first dielectric layer having a first dielectric thickness covering the first metal core, and the first A second metal having a first lead wire and a second metal core diameter having a first outer metal layer covering the dielectric layer, wherein the first outer metal layer is grounded A core, a second dielectric layer having a second dielectric thickness covering the second metal core, and a second outer metal layer covering the second dielectric layer, A second lead wire, wherein the second outer metal layer is grounded, and Result, the first and second lead wires reduces the susceptibility to EMI and crosstalk between the first and second leads.

  Furthermore, the present invention is directed to a die package, the die package including a die having a plurality of connection pads, a die substrate supporting a plurality of connection elements, a first metal core having a first metal core diameter, A first dielectric layer having a first dielectric thickness covering the first metal core, and a first outer metal layer covering the first dielectric layer; A first lead wire having a first ground plane attached to the metal layer, a second metal core having a second metal core diameter, and a second dielectric thickness covering the second metal core And a second outer metal layer covering the second dielectric layer, and a second ground plane is attached to the second outer metal layer. 2 lead wires, so that the first and second lead wires are 1 and to reduce the susceptibility to EMI and cross talk between the second lead. The first lead may extend from the first die to one of a plurality of connecting elements on the die substrate, and / or the second lead from the second die to the die substrate One of the plurality of connection elements may be extended. The second ground plane may or may not overlap with the first ground plane. In the case of superposition, an intermediary layer that maintains electrical insulation may be disposed between the first ground plane and the second ground plane.

  Further, the die package according to the present invention may be a stacked die package having a first die and a second die, each die having a plurality of connection pads, and the first lead wire being the first lead wire. Extending from one of the plurality of connection pads of one die to one of the plurality of connection elements on the die substrate, or of the plurality of connection pads of the second die And the second lead extends from one of the plurality of connection pads of the second die to one of the plurality of connection elements on the die substrate, Alternatively, it extends to one of the plurality of connection pads of the first die.

  The dependent claims are directed to embodiments that are advantageous for die packages according to the present invention, and each feature disclosed therein may be added individually or in combination.

  The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The drawings are for illustration purposes only and are not drawn to scale. The invention itself, however, will be best understood by reference to the following detailed description in conjunction with the accompanying drawings in both construction and method of operation.

FIG. 6 is a view of a fine pitch low crosstalk die package with a dielectric coated lead having an outer grounded metal coating. FIG. 5 illustrates a low crosstalk overlapping dielectric coated lead having an outer grounded metal coating. It is a figure which shows the low crosstalk lead wire used with a stacked die package. FIG. 6 illustrates a low crosstalk lead used in a die-to-die or package-to-package embodiment. FIG. 6 is a block diagram illustrating method steps for manufacturing a dielectric coated lead having an outer grounded metal coating. FIG. 6 illustrates a subtractive method of manufacturing a dielectric coated lead having an outer grounded metal coating. FIG. 4 shows a BGA package with a dielectric coated lead having an outer grounded metal coating. FIG. 5 shows a portion of a leadframe package with a dielectric coated lead having an outer grounded metallization. It is a figure which shows the S parameter measurement of the crosstalk level based on a frequency. FIG. 4 shows EM fields associated with a single lead and a differential lead with a dielectric coating and an outer grounded metal layer, respectively. FIG. 5 shows a die package according to the present invention having dielectric and metal coated lead wires connected to separate ground planes that may or may not overlap. FIG. 2 shows a die package according to the present invention having two ground planes. FIG. 6 is a diagram illustrating another embodiment in which two ground planes form an RF ground shield and a DC power shield, respectively.

  In describing the preferred embodiment of the present invention, reference will be made to FIGS. 1-13 of the drawings wherein like parts have the same features of the present invention.

  Lead wires having an electromagnetic shield and having one or more intermediate dielectric layers between a metal core and a conductive outer layer that can be grounded are used to improve the electrical performance of the package. This is depicted in FIG. 1 illustrating a die package 150 having a die 152 attached to a substrate 154 with different length leads 156. As can be seen from the figure, the connection pads 158 on the substrate 154 usually have a larger spacing than the chip side in consideration of the process. The spacing of the die pad is commonly defined according to the pitch that can be realized by the wire bonding machine. On the board side, it is defined by the lithographic reproducibility of the printed circuit board (PCB) type process and the placement accuracy of solder, pins or wiring elements. In practice, the wires are placed closer to the chip than to the package. This means that as the die size decreases, undesirable electromagnetic field coupling (crosstalk) occurs, particularly near the die. In addition to reducing electromagnetic interference (EMI) within the package, the leads formed as described herein reduce the sensitivity of external EMI (of the package), as well as electromagnetic emissions. Is also substantially reduced.

  As shown in FIG. 2, the semiconductor die packaging system 100 includes leads 110, 112 and 114 having low electromagnetic emissions and crosstalk due to the structure of the leads. The die 120 mounted on the substrate 102 has multiple connection pads 122 for signals, power, or other functionality required by the die 120. The substrate 102 may include conductive pads 104 that provide a conductive path from the package directly or by a conductive lead frame, filled vias, conductive traces, secondary level wiring, and the like. Leads 110, 112 and 114 are connected to conductive pad 104 and may have substantially different lengths as shown. As shown in FIG. 2, the leads are densely arranged and can be crossed or placed vertically (eg, leads 110 and 112 are drawn crossing), which creates many undesirable electromagnetic coupling possibilities. Have.

  In the embodiment shown in FIG. 2, leads 110, 112 and 114 have an inner core and an outer metal layer. For example, the leads 110, 112 and 114 have a metal core of a defined diameter along their length, and the metal core is sequentially coated with a thin dielectric layer and a conductive metal layer. Compared to bare leads of the same size and without additional dielectric and metallization, leads 110, 112 and 114 emit less radiation and are less sensitive to external EMI (of the package). Crosstalk is less likely to occur. Due to the superior electrical characteristics of the lead configuration as disclosed in certain embodiments, leads having different core lengths but the same core diameter will have substantially the same noise reduction compared to bare wire. Can have. It can be seen that the measured noise reduction is greater than 5 dB and 30 dB compared to the dielectric and bare lead without the metal layer (s) covering the dielectric. In certain embodiments, EMI resistance is effective over a range of lead lengths, and two leads can have the same cross-sectional structure and impedance, while one lead has the same EMI characteristics. Is 10 times the length of the other lead wire.

  Electromagnetic fields leading to unnecessary crosstalk are not generated only by side-by-side leads, but may also be generated by leads adjacent to each other in a stacked configuration. This is realized with the stacked die shown in FIG. 3, which is shown side-by-side when bare wires are used instead of leads coated with a dielectric layer and a conductive metal layer as described herein. Alternatively, a stacked die package 160 is shown that includes dies 162a-d having exemplary leads 164a-d and 166a that result in unacceptable crosstalk from the vertically disposed leads. Similarly, FIG. 4 shows die stacks 170 and 172 having die-to-die lead connections 174 and die-to-substrate connections 176. There may be a die-to-die direct connection 178 in separately implemented packaging systems 180, 182 with reduced crosstalk.

  Dielectric coated leads used in semiconductor die packaging can be formed to have different dielectric thicknesses. Both core diameter and dielectric thickness can be varied. In certain embodiments, the composition of the coating dielectric can also be varied. This allows, for example, high performance dielectrics with excellent vapor barrier, oxygen decomposition resistance, etc. to be thinly deposited on a thick layer of low cost dielectric material. In another aspect of the illustrated embodiment, the leads 110, 112 and 114 (see FIGS. 2 and 3) have different dielectric thicknesses across the inner core and outer metal layer, which separately provide different impedances. To do. For example, the lead 110 may have a metal core of a defined diameter along its length, and the metal core is sequentially coated with a thin dielectric layer and a conductive metal layer. Such a lead 110 is suitable for power transmission because the resulting low impedance and low capacitance reduce power loss. Alternatively, lead 112 has a thicker dielectric layer suitable for transmission of signal data, while lead 114 has an intermediate thickness of dielectric layer. In certain embodiments, due to the superior electrical properties of the disclosed lead structure, lead wires having substantially different lengths but the same core diameter have different lengths by more than 50%, It is possible to have substantially the same impedance within 10% of the target impedance. For example, the lead 116 can have substantially the same impedance as the lead 110 even though it is twice as long as the lead 110. In certain embodiments, the lead wire difference may be even greater, and the two lead wires have the same cross-sectional structure and impedance, but the length of one lead wire is the length of the other lead wire. 10 times.

  In general, a thin dielectric layer provides a low impedance useful for power line applications, a thick dielectric layer is generally effective for signal transmission quality, and the outer metal layer on the lead is effectively connected to the same ground Is done. A combination of core diameter and dielectric thickness is possible, and a series of such steps may be performed to achieve a lead having separate impedances. In certain embodiments, the power line is used to increase power handling capability, lower power line temperature, and / or further reduce inductance to the power supply and ground line that will exacerbate ground potential fluctuations or power degradation. It is desirable to provide a large-diameter core.

  Intermediate thickness dielectric layers are also useful because it is effective for many packages to have leads having three or more different dielectric thicknesses. In order to maximize power transfer, a lead having an intermediate dielectric thickness can be used to connect a power source and a load of substantially different impedance. For example, a 10 ohm power supply may be connected to a 40 ohm load with a 20 ohm lead. In addition, because the dielectric cost can be high, important signal paths can be routed using thick dielectrics, while less important or reset leads, etc. It is coated with a dielectric layer that is thicker, but thinner (intermediate) than the critical signal leads.

  The exact thickness of the dielectric coating can be selected in combination with the wire bond diameter to achieve the desired specific impedance value for each lead.

The impedance of the characteristic of the coaxial line is expressed by Equation (1), where L is the inductance for each unit length, C is the capacitance for each unit length, and a is the bond wire Is the diameter, b is the outer diameter of the dielectric, and ε _γ is the relative dielectric constant of the coaxial dielectric.

  As shown in FIG. 5, in one embodiment, the fabrication of a dielectric coated lead with an outer grounded metallization with or without one or more ground planes is shown in block diagram 200. You can proceed using the following steps: In a first step 202, the connection pads are cleaned on the die and substrate. Next, the die is connected to the connection pad using a wire bonder (204). Optionally, a second diameter wire (eg, a larger diameter wire suitable for power connection) may be attached (206) or the area of the die to allow selective coverage May be masked or otherwise protected (step 208). One or more layers of dielectric of the same or different composition may be coated (step 210), followed by a dielectric portion to allow access to the ground connection coated in dielectric coating step 210. A selective laser or thermal ablation or chemical removal is performed (step 212). This step is optional because in some embodiments the need for ground vias can be eliminated. This is particularly suitable for dies operating at high frequencies since virtual RF grounding can be achieved by capacitive coupling and the frequency dependence on the thickness value (a function of Er) allows ground establishment by capacitive coupling. Next, metallization is performed (214), the dielectric is covered with a metal layer that forms the outermost metallization layer of the lead wire, and the lead wire is grounded. This entire process may be repeated a number of times (step 216), which is useful for embodiments using selectable coating techniques, and particularly in embodiments using multiple dies or complex and different impedance leads. It is valid. In the final step (step 218), for non-cavity packages, overmolding can be used to seal the leads. Sealed leads are those that can be used in the high frequency device packages described in US Pat. No. 6,770,822 and US 2012/0066894, and their disclosure. May be used with reference to

  In particular embodiments, changes and additions to the described processes are possible. For example, dielectric conformal coating can be achieved by chemical (electrophoresis), mechanical (surface tension), catalytic primer, electromagnetic (UV, IR), electron beam, and other suitable techniques. Electrophoretic polymers can be easily made to exact thicknesses by adjusting process parameters and / or simply by applying additive, concentration, chemical, thermal or timing changes to the electrophoretic coating solution. This is particularly advantageous because it depends on the self-inhibiting reaction that can be coated.

  In another embodiment, the lead may be formed using a bond wire pre-coated with a dielectric. Commercially coated wires are typically thinner than the dielectric thickness required to produce, for example, a 50 ohm lead, but are discussed above to increase the dielectric thickness to set the desired impedance. A dielectric coating step can be used. The use of these pre-coated wires simplifies other process steps required to form coaxial leads and requires a thinner layer of deposited dielectric and faster processing time to form ground vias. Enable. Pre-coated bond wires can be used to prevent shorts in tight or intersecting leads. In certain embodiments, the pre-coated bond wire may have a dielectric made of a photosensitive material to allow selective patterning techniques.

  In another embodiment, dielectric parylene can be used. Parylene is used as a moisture barrier and dielectric barrier and is the trade name for a variety of chemical vapor deposited poly (p-xylene) polymers. Parylene can be formed in a growth-inhibited condensation reaction using a modified parylene coating system, in which the die, substrate and lead are aligned with the photosensitive plate, which is EM radiation (IR, UV or Others) closely collide, providing a selective dielectric growth rate. This can effectively reduce or eliminate the need for processes such as contact via formation and parylene bulk removal.

  Parylene and other dielectrics are known to undergo oxygen scission decomposition in the presence of oxygen, water vapor and heat. Damage can be limited by a metal layer that forms an excellent vapor oxygen barrier with a 3-5 micron thick thin film layer that can form a truly hermetic interface. Alternatively, a wide range of polymer-based vapor oxygen barriers can be used if the metal is selectively removed due to electrical, thermal, or manufacturing requirements, or if the metal does not cover a specific area Among them, polyvinyl alcohol (PVA) is one widely used polymer. These polymers may be sprayed onto a parylene surface exposed to a glob topping process, a screen printing process, a stencil process, a gantry distribution process, an oxygen or water vapor environment. Advantageously, the use of a vapor barrier polymer can be part of a cost-reduction strategy because otherwise expensive parylene or oxygen sensitive materials are required.

  As will be appreciated, all described method steps enjoy the advantages of various selectable coating techniques. Selectable coatings can be physical masking, directional polymer deposition, photoresist methods, or any other suitable coating that guarantees different coating thicknesses in the metal core, dielectric layer or other outermost layer when coated. A method may be used. With selectable coatings, lead construction is possible with additive methods, but subtractive methods are also possible, where the dielectric or metal is removed to form wires of different impedances. For example, a package in which one or more dies are arranged may be appropriately wire-bonded for wiring of all packages and device pads. As shown in connection with FIG. 6, which shows the steps and structures related to die package manufacturing, the dielectric coating 300 can be coated to a predetermined thickness over the wirebond metal conductor 302 (step A), The predetermined thickness is the thickness of the dielectric required for the secondary wiring impedance. The secondary impedance wire bond dielectric can be removed, for example, by an etching step (Step B), followed by a second coating 304 coating (Step C), followed by a metal coating 306 of both wires ( Step D). This subtractive process creates two independent impedance wire bonds.

  The embodiment shown in FIG. 7 shows a ball grid array (BGA) package 410 having a number of selected impedance dielectric and metal coated leads 412, 414. BGA is a surface mount packaging that is widely used in integrated circuits and generally has more wiring than dual in-line, leadframe or other flat packages because the entire bottom surface of the BGA can be used for connection pads. Can provide pin. In many types of BGA packages, the die 416 is attached to a substrate 418 having fillable vias 420 connected to connection pads. Leads 412, 414 are used to connect top die 416 to pad / via 420, thereby providing an electrical connection from the top side to the bottom of substrate 418. In a BGA package, solder balls 422 are attached to the bottom of the package and held in place with adhesive flux until soldering to a printed circuit board or other board. As described herein, the wire bond of a conventional BGA package can be replaced with an improved lead having a dielectric layer and a metal layer that can be externally grounded. The lead can have a dielectric thickness that varies across the inner core and the outer metal layer so that the dielectric layer thickness is partially different or has a specific impedance selected to better fit. It can be selectively optimized. As shown in FIG. 7, both long leads 412 and short leads 414 are supported.

  More particularly, improved BGA package assembly may require die surface up attachment to a substrate that supports connection pads formed adjacent to and around the vias of the substrate. . This assembly is appropriately wirebonded for each required wiring, and wirebonds are formed between the connection pads on the substrate and the connection pads on the die. The low frequency and power inputs are connected to the low frequency signal lead, while the high frequency input and output are connected to the high frequency signal lead. In some embodiments, the low frequency and power input leads may have a different thickness than the high frequency signal leads. The assembly is then basically covered with a conformal dielectric material. Parylene is used because of its low cost, ease of vacuum deposition, and excellent performance characteristics. A portion of the dielectric layer near the lead frame attachment location is selectively removed by etching, thermal degradation, and laser ablation to make an electrical connection to a ground connection point or ground shield layer. Similarly, a portion of the dielectric layer is removed near the die connection pad to allow ground connection. Following the application of the metallization layer on the dielectric layer, a structural ground connection is made to form a ground shield. The preferred metal layer thickness should be selected in view of skin depth and DC resistance, and should be composed primarily of excellent conductors such as silver, copper, or gold. For most applications, a 1 micron coating thickness is sufficient for functionality, but a thicker coating helps reduce crosstalk between leads. These coatings can be applied to defined areas by a combination of lithography or other masking methods and plating or other selectable coating methods. The package can be completed by placing an overmold or lid on the die and then undergoing dicing (singulation) and inspection.

  Alternatively, in the embodiment shown in FIG. 8, a low cost lead frame based on a die package 440 with wire bonds extending from the die to the lead frame comprises a two-dimensional array of individual package sites and an outer frame. It can be manufactured by forming a lead frame strip having a portion. Leadframe processing is conventional and can be formed by etching, punching or electrodeposition of separate lead wires. The leadframe strip can be placed in a mold including but not limited to injection molding or transfer molding equipment. A suitable dielectric material, preferably plastic, such as a commercially available epoxy mold compound, is injected, pumped or transferred to the mold to achieve a leadframe / mold material composite structure. The properties of the mold materials are important for their dielectric constant, loss tangent and electrical dispersion properties and their temperature, humidity and other mechanical performance attributes.

  Each package site of the resulting composite leadframe strip is prepared for metallization coating over the exposed metal portion of the leadframe with the mold release agent and / or burrs removed. This can be achieved by plating techniques such as immersion or electroplating, and the metal is selected to facilitate corrosion inhibition and wire bond bonding. An example of such a finish is a nickel thin film layer (for protection) followed by a gold layer (additional protection and wirebond capability). Next, each package site of the resulting molded leadframe strip is placed with the necessary dies and attached to the bottom, and the die attach material has mechanical and thermal properties that correspond to the specific packaging application. Selected by. The resulting assembly is then wirebonded as appropriate for each required wiring, and wirebonds are formed between the lead wires on the lead frame and the connection pads on the die. The low frequency and power input is connected to the low frequency signal lead, while the high frequency input and output is connected to the high frequency signal lead. In some embodiments, the low frequency and power inputs may be of a different thickness than the high frequency signal lead.

  Similar to the BGA package 410 described above, the resulting leadframe strip is coated with a basically conformal dielectric material including parylene. In the case of parylene, the bottom of the package is masked with a tape such as a vacuum-compatible polyimide with an acrylic adhesive or a similar material in order to prevent adhesion to the lead wire portion finally attached to the PCB. It is preferable. This allows easier soldering in subsequent steps. A portion of the dielectric near the lead frame attachment location is selectively removed by etching, thermal degradation or laser ablation to make an electrical connection to the ground contact or ground shield layer. Similarly, a portion of the dielectric layer near the die connection pad is removed to allow ground connection. Following application of the metallization layer from above the dielectric layer, a structural ground connection is applied to form a ground shield. The preferred metal layer thickness should be selected in view of DC resistance and skin depth, and should be composed primarily of excellent conductors such as silver, copper or gold. For most applications, a coating thickness of 1 micron is adequate for functionality, but a thicker coating helps to reduce crosstalk between leads. These coatings can be applied to the defined areas by a combination of lithography or other masking methods and plating or other selectable coating methods. The package is completed by placing an overmold or lid on the die, followed by dicing (singulation) and inspection.

Example 1-Crosstalk Performance FIG. 9A is a graph 500 comparing the crosstalk characteristics as a function of frequency for a bare wire bond 502, a 30 ohm coaxial line 504, and a 50 ohm coaxial line 506. Both coaxial leads show about 25 dB improved crosstalk / insulation characteristics compared to unshielded wiring. In this regard, even mismatched coaxial leads made according to the present invention are superior to unshielded bare leads.

  FIG. 9B is a graph 510 depicting a comparison in the time domain of bare wire bonds 512, 514 and 50 ohm coaxial leads 516, 518. Consistent with the frequency results depicted in FIG. 9A, the noise voltage is reduced by a factor of 12 (520) (crosstalk / isolation) and the settling time response is improved by a factor of 7 (522) (increase in bandwidth) Possible).

  FIGS. 10A to 10D show the space of the EM field amplitude for the single lead and the differential lead, respectively, with and without the dielectric coating and the metal layer grounded on the outside. An amplitude plot is shown. FIG. 10A shows an amplitude plot 600 of a single end bond wire 602. As shown, the EM field amplitude at a point along the y-axis of the bond wire is significant. FIG. 10B shows an amplitude plot 610 of the single-ended microcoaxial line 612. As can be seen, the coaxial wire has substantially reduced electromagnetic emissions compared to the bare lead wire.

  This is particularly useful for differential pairs, a technique commonly used with bare leads to improve noise immunity. A pair of leads driven with signals of opposite polarity are typically exposed to an approximately equal noise environment. When these two signals are applied differentially together, the common noise is canceled out. However, if the noise environment is unequal, as can occur with fine-pitch placement of many pairs of leads, adjacent noise sources will cause a larger signal to the nearest neighboring differential pair than to the farther neighboring differential pair. May induce. Thus, since the shielded micro coaxial pair is greatly attenuated before the noise reaches the signal line, the resistance against the noise is considerably high. FIG. 10C shows a spatial amplitude plot 630 of the differential micro coaxial line 632. The plot shows an almost perfect shield, ie the emission of very little electromagnetic radiation.

  As shown in FIGS. 11A and 11B, the semiconductor die packaging system 1100 is formed to have a large number of ground planes that are separated or overlapped. Leads 1110, 1112 and 1114 are manufactured to have low electromagnetic emissions and crosstalk for connection to the lead structure and ground plane. The die 1120 mounted on the die substrate 1102 has multiple connection pads 1122 for signals, power or other functionality required for the die 1120. The die substrate may have conductive pads 1104 provided with conductive paths from the package directly or by conductive lead frames, filled vias, conductive traces, second level wiring, and the like. Leads 1110, 1112 and 1114 are connected to conductive pads 1104 and may have substantially different lengths as shown.

  In the embodiment shown in FIG. 11A, the lead wires 1110, 1112 have an inner core and an outer metal layer connected to the first ground plane 1130. In contrast, lead 1114 is separate from the inner core and first ground plane 1130 and has an outer metal layer connected to a separate second ground plane 1132. Similarly, FIG. 11B shows a package 1101 that is identical to the design of package 1100 except that ground planes 1134 and 1136 physically overlap. However, both ground planes are electrically independent because a dielectric coating 1138 (shown partially removed) is used to insulate the grounds 1134 and 1136 from each other. As will be appreciated, the leads 1110, 1112 and 1114 have a metal core of a defined diameter along their length, which is sequentially covered with a dielectric layer and a conductive metal layer.

  Leads 1110, 1112 and 1114 are less radiated, less sensitive to external EMI (of the package) and more crosstalk than the same size bare lead without additional dielectric and metallization Hard to occur. In certain embodiments, due to the superior electrical properties of the lead configured as disclosed, leads having different core lengths but the same core diameter may have substantially the same noise relative to bare wire. A reduction can be obtained. The measured noise reduction is greater than 5 dB and up to 30 dB compared to a bare lead without a dielectric and coated metal layer. In certain embodiments, EMI resistance is effective over a range of lead lengths, and two leads can have the same cross-sectional structure and impedance, while one lead has the same EMI characteristics. Is 10 times the length of the other lead wire.

Example 2, Example 3, Example 4—Crosstalk Performance Example 2 FIG. 12 shows an example of an embodiment having two ground planes 1200, 1202, both allowing connection at both lead ends. For this purpose, it extends from the package substrate 1204 to the die 1206.

  Example 3 FIG. 13 shows an example of an embodiment in which two ground planes form an RF ground shield 1300 and a DC power ground shield 1302, respectively.

  Example 4-In another embodiment, multiple impedance wiring is realized by a variation of the above process. The substrate supporting the die may be appropriately wire bonded with 0.7 mm wire for wiring of all packages and device pads. The resulting package assembly receives a 1.31 micron coating of Parylene C dielectric. A process is performed to open a power ground connection on the package and a via corresponding to the power ground connection on the device. A first selective metallization process is performed that forms metal only in areas related to power wiring and their associated ground. This selective metallization can be achieved by physical masking, lithography or other selective processes. In this way, a complete 5 ohm coaxial wiring is formed. In this case, a second coating of dielectric is deposited to achieve a total dielectric thickness of 26.34 microns. The second via process is executed for all the grounds required for the signal lines. This step may have a connection to power ground if necessary. A second metallization is performed to form a ground shield for 50 ohm lines. In this way, a combination of 5 ohms and 50 ohms is realized with the option of separating the power and signal line ground planes separately.

  While preferred embodiments specific to the present invention have been described in detail, it will be apparent to those skilled in the art that many alternatives, modifications, and variations are possible in light of the foregoing description. Accordingly, the appended claims are intended to cover such alternatives, modifications, and variations as fall within the scope and scope of the present invention.

  In particular, the present invention is directed to a stacked die package having excellent EMI performance, which die package supports first and second dies each having a plurality of connection pads, and a plurality of connection elements. A first lead wire extending from the first die to one of a plurality of connection elements on the die substrate, wherein the first metal core has a first metal core diameter; A first dielectric layer having a first dielectric thickness covering the metal core, a first lead having an outer metal layer connected to ground, and a plurality of on the die substrate from the second die. A second lead wire extending to one of the connecting elements, a second metal core having a second metal core diameter, and a second dielectric thickness covering the second metal core; A second dielectric layer, and a first layer having an outer metal layer connected to ground. And a lead wire, the sensitivity of EMI and cross talk between the first and second lead wire is reduced.

  In the above die package, the first lead wire overlaps the second lead wire.

  In the die package described above, the first lead is on the second lead.

  The die substrate may have vias filled to allow formation of a BGA package.

  The die substrate may have a lead frame to form a lead frame package.

  The present invention has a die to substrate connection as well as a die to die connection.

  Furthermore, the present invention provides a die having a plurality of connection pads, a die substrate supporting a plurality of connection elements, a metal core, a dielectric layer covering the metal core, and an outer metal layer connected to ground. A BGA package with excellent EMI performance that has a crosstalk noise reduced by 5 dB or more compared to a lead wire that has a plurality of lead wires and has a dielectric layer covering the metal core and no outer metal layer And

  Furthermore, the present invention has a differential pair with reduced crosstalk and a crossover type long loop out-of-plane lead wire with reduced crosstalk.

  The present invention further includes a die having a plurality of connection pads, a die substrate supporting the plurality of connection elements, and a first die extending from the first die to one of the plurality of connection elements on the die substrate. A lead wire having a first metal core having a first metal core diameter, a first dielectric layer having a first dielectric thickness covering the first metal core, and an outer metal layer A first lead wire, a first ground plane attached to an outer metal layer of the first lead wire, and a second extending from the second die to one of a plurality of connecting elements on the die substrate. A second lead wire having a second metal core having a second metal core diameter and a second dielectric layer having a second dielectric thickness covering the second metal core And a second ground plane attached to the outer metal layer of the second lead wire. Having a die package.

  In the die package described above, the second ground plane may overlap the first ground plane while the intermediary dielectric layer maintains electrical insulation between the first and second ground planes.

The die package may be constructed in the form of a BGA package and / or a lead frame package.

The above and other objects that will be apparent to those skilled in the art are achieved by the present invention directed to a die package for EMI attenuation, the die package comprising a die having a plurality of connection pads and a plurality of connection elements. A die substrate that supports the first metal core, a first metal core having a first metal core diameter, a first dielectric layer having a first dielectric thickness covering the first metal core, and the first a dielectric layer having a first outer metal layer covering the first lead wire of the first outer metal layer that is connected to the first ground plane, a second metal core diameter A second metal core; a second dielectric layer having a second dielectric thickness covering the second metal core; and a second outer metal layer covering the second dielectric layer. and, of connection to the second outer metal layer is a second ground plane And a second lead Ru Tei, so that the first and second lead wires reduces the susceptibility to EMI and crosstalk between the first and second leads.

Further , the first lead may extend from the first die to one of the plurality of connecting elements on the die substrate, and / or the second lead may be die from the second die. It may extend to one of a plurality of connecting elements on the substrate. The second ground plane may or may not overlap with the first ground plane. In the case of superposition, an intermediary layer that maintains electrical insulation may be disposed between the first ground plane and the second ground plane.

Electromagnetic fields leading to unnecessary crosstalk are not generated only by side-by-side leads, but may also be generated by leads adjacent to each other in a stacked configuration. This is realized with the stacked die shown in FIG. 3, which is shown side-by-side when bare wires are used instead of leads coated with a dielectric layer and a conductive metal layer as described herein. or it shows a stacked die package 160 comprises a die 162a-d having exemplary leads 164a-d and 166a -d crosstalk unacceptable from lead in the vertical arrangement occurs. Similarly Figure 4 shows a lead 1 74 connected from the die to the die, the die stack 170 and 172 and a lead wire 176 which is Connect from the die to the substrate. There may be a lead wire 178 that is directly connected from the die of reduced within the packaging system 180, 182 that are separately mounted with crosstalk to die.

Dielectric coated leads used in semiconductor die packaging can be formed to have different dielectric thicknesses. Both core diameter and dielectric thickness can be varied. In certain embodiments, the composition of the coating dielectric can also be varied. This allows, for example, high performance dielectrics with excellent vapor barrier, oxygen decomposition resistance, etc. to be thinly deposited on a thick layer of low cost dielectric material. In another aspect of the illustrated embodiment, the leads 110, 112 and 114 (see FIGS. 2 and 3) have different dielectric thicknesses across the inner core and outer metal layer, which separately provide different impedances. To do. For example, the lead 110 may have a metal core of a defined diameter along its length, and the metal core is sequentially coated with a thin dielectric layer and a conductive metal layer. Such a lead 110 is suitable for power transmission because the resulting low impedance and low capacitance reduce power loss. Alternatively, lead 112 has a thicker dielectric layer suitable for transmission of signal data, while lead 114 has an intermediate thickness of dielectric layer. In certain embodiments, due to the superior electrical properties of the disclosed lead structure, lead wires having substantially different lengths but the same core diameter have different lengths by more than 50%, It is possible to have substantially the same impedance within 10% of the target impedance. For example, the leads 11 2, despite twice the lead wire 110 length, it is possible to have substantially the same impedance as the lead 110. In certain embodiments, the lead wire difference may be even greater, and the two lead wires have the same cross-sectional structure and impedance, but the length of one lead wire is the length of the other lead wire. 10 times.

This is particularly effective for the differential pair (622) , which is a technique commonly used with bare leads to improve noise immunity (FIG. 10C) . A pair of leads driven with signals of opposite polarity are typically exposed to an approximately equal noise environment. When these two signals are applied differentially together, the common noise is canceled (620) . However, if the noise environment is unequal, as can occur with fine-pitch placement of many pairs of leads, adjacent noise sources will cause a larger signal to the nearest neighboring differential pair than to the farther neighboring differential pair. May induce. Thus, since the shielded micro coaxial pair is greatly attenuated before the noise reaches the signal line, the resistance against the noise is considerably high. FIG. 10 ( D ) shows a spatial amplitude plot 630 of the differential micro coaxial line 632. The plot shows an almost perfect shield, ie the emission of very little electromagnetic radiation.

Claims (18)

A die (152; 120; 162a-d; 170; 416) having a plurality of connection pads;
A die substrate (154; 102; 418) supporting a plurality of connecting elements;
A first metal core having a first metal core diameter; a first dielectric layer having a first dielectric thickness covering said first metal core; and covering said first dielectric layer A first lead (156; 110; 164a; 166a; 176; 412) having a first outer metal layer, the first outer metal layer being connected to ground or a first ground plane;
A second metal core having a second metal core diameter; a second dielectric layer having a second dielectric thickness covering said second metal core; and covering said second dielectric layer A second lead (156; 112; 164b; 166b; 176; 414) having a second outer metal layer, the second outer metal layer being connected to ground or a second ground plane; Prepared,
A die package (150; 100; 160; 180; 182; 410; 440; 1100) with reduced susceptibility to EMI and crosstalk between the first lead and the second lead. The die package has a first die and a second die, and each of the first die and the second die has a plurality of connection pads,
The first lead wire extends from the first die to one of the plurality of connection elements on the die substrate, or of the plurality of connection pads of the second die And the second lead extends from the second die to one of the plurality of connecting elements on the die substrate, or the plurality of the first die. The die package of claim 1, wherein the die package extends to one of the connection pads.   The die package according to claim 2, wherein the die package is a stacked die package.   The first lead (1110, 1112) extends from a first die to one of the plurality of connection elements on the die substrate (1102), and the second lead (1114) is Extending from the second die to one of the plurality of connection elements on the die substrate (1102), the first ground plane (1130, 1136) being attached to the first outer metal layer The die package (1100) according to any of claims 1 to 3, wherein the second ground plane (1132, 1134) is attached to the second outer metal layer.   The second ground plane (1134) is preferably configured such that the intermediate layer (1138) maintains the electrical insulation between the first ground plane and the second ground plane, while the first ground plane (1136) is maintained. The die package (1100) of claim 4, wherein   The die package according to claim 1, wherein the first metal core diameter is different from the second metal core diameter.   The die package according to claim 1, wherein the first metal core diameter is the same as the second metal core diameter.   The die package according to claim 1, wherein the first dielectric thickness is different from the second dielectric thickness.   The die package according to claim 1, wherein the first dielectric thickness is the same as the second dielectric thickness.   10. The die package according to any one of claims 1 to 9, wherein the die substrate has a filled via that allows formation of a BGA package.   The die package according to any one of claims 1 to 9, wherein the die substrate includes a lead frame that forms a lead frame package.   The die package according to any one of claims 1 to 11, wherein the first lead wire intersects the second lead wire and / or is on the second lead wire. The first lead has a first length and a first impedance; the second lead has a second length and a second impedance;
The die package according to any one of claims 1 to 12, wherein the first length is different from the second length and / or the first impedance is different from the second impedance.   The die package according to any one of claims 1 to 13, wherein the first metal core and / or the second metal core are sequentially covered with a dielectric layer and a conductive metal layer.   15. A die package according to any one of the preceding claims, wherein the lead wire provides electrical communication for die-to-die connection and / or die-to-substrate connection.   The die package according to any one of claims 1 to 15, wherein the plurality of lead wires have at least one differential pair.   The die package according to claim 1, wherein the plurality of lead wires have crossover type long loop out-of-plane lead wires with reduced crosstalk.   18. A BGA package with excellent EMI performance comprising the die package according to any one of claims 1 to 17, wherein the die package has a plurality of lead wires, each lead wire having a metal core. And a dielectric layer that covers the metal core, and an outer metal layer that is connected to ground, and at least crosstalk noise is lower than a lead wire that does not have a dielectric layer that has an outer metal layer that covers the metal core. BGA package reduced by 5 dB.

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